A variety of different needle tip protectors have been developed or proposed to protect, i.e., to enclose or otherwise shield, sharp needle tips in recognition of the need to reduce or eliminate accidental needle-sticks. Some needle tip protectors include mechanisms having many different cooperating parts. Such needle tip protectors are often unreliable and difficult to manufacture. Other needle tip protectors require the healthcare worker to activate the protection device through a trigger mechanism or other activator. Thus, instead of being passively activated, such devices require additional steps before they offer protection. Still other needle tip protectors require longer needles than normally would be used in a nonprotected version for their respective gauge, especially where the needle protector is large and consumes some of the available axial length of the needle. Still others require alteration of the shape or surface of the needle or tethering or other attachment to the cannula hub to prevent the needle tip protector from coming off the needle.
One example of a needle tip protector is described in U.S. Pat. Nos. 5,328,482 and 5,322,517. These patents disclose the broad concept of a coil spring disposed about a needle shaft in a wound state, and which can unwind to grip the needle shaft. More specifically, the needle is disposed through a passageway formed by the interior of the coil spring. One end of the spring is fixed relative to the other end, and may be rotated (“wound”) against the rotational bias of the spring to expand the diameter of the passageway. Upon release, the spring unwinds to reduce the diameter of the passageway to grip the needle shaft.
However, the needle tip protector of U.S. Pat. Nos. 5,328,482 and 5,322,517 involves many components and cooperating parts and thus involves complex and costly manufacture. For example, the spring is held in its wound configuration by a separate rotational latch and will unwind only upon release of this separate latch. Further, the housing of the device includes concentric outer and inner cores. The outer core is moved relative to the inner core to wind the spring. Once the latch has been released to allow the spring to unwind and grip a needle, these cores must be prevented from moving relative to one another to prevent inadvertent rewinding of the spring. Thus, a second spring that prevents rotation of the outer core is provided. As a result, this needle tip protector suffers the drawbacks of complexity described above.